The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Air is drawn into an engine through an intake manifold. A throttle valve controls airflow into the engine. The air mixes with fuel from one or more fuel injectors to form an air/fuel mixture. The air/fuel mixture is combusted within one or more combustion chambers of the engine. Combustion of the air/fuel mixture is initiated by spark provided by a spark plug.
The compression ratio of a combustion chamber refers to a ratio of a maximum volume of the combustion chamber to a minimum volume of the combustion chamber. In an internal combustion engine, the minimum volume may occur when a piston is in a topmost position (referred to as top dead center or TDC). The maximum volume may occur when the piston is in a bottom most position (referred to as bottom dead center or BDC). If, for example, the minimum volume of the combustion chamber is 1 unit of volume and, for example, the maximum volume of the combustion chamber is 10 units of volume, the compression ratio of the combustion chamber may (theoretically) be approximately 10 to 1 (10:1).